necrotising fasciitis – caused by a serious bacterial infection that spreads quickly through the deeper layers of skin and tissue

internal gangrene – where the blood flow to an internal organ, usually the intestines, gallbladder or appendix, becomes blocked

Who's most at risk?

People most at risk of gangrene are those with an underlying health condition that can affect the blood vessels and arteries (particularly if it's poorly managed), and those with a weakened immune system.

Conditions affecting the blood vessels

Conditions that can affect the blood vessels and increase your risk of developing gangrene include:

diabetes – a lifelong condition that causes a person's blood sugar level to become too high, which can damage nerves and blood vessels (see below)

atherosclerosis – where arteries narrow and become clogged with a fatty substance known as plaque

Raynaud's – where blood vessels in certain parts of the body, usually the fingers or toes, react abnormally to cold temperatures

As blood vessels are naturally narrow, any damage or extra narrowing has the potential to block blood flow to a part of the body and cause gangrene.

Diabetes

People with diabetes have an increased risk of developing gangrene. This is because the high blood sugar levels associated with the condition can damage your nerves, particularly those in your feet, which can make it easy to injure yourself without realising.

High blood sugar can also damage your blood vessels, restricting the blood supply to your feet. Less blood means your feet will also receive fewer infection-fighting cells, so wounds will take longer to heal and are more likely to become infected.

It's therefore important that you take extra care of your feet if you have diabetes. Read more about foot care in preventing gangrene.

Injuries and surgery

You're also at an increased risk of developing gangrene if you experience a traumatic injury or serious damage to your skin and tissues, such as:

These injuries can cause a sudden loss of blood to an area of your body, and any open wounds can become infected with bacteria.

Gangrene can also occur as a result of an infection that develops during surgery. However, with advances in surgical techniques and infection control, the chances of gangrene developing during surgery are small nowadays.

Weak immune system

If your immune system is seriously weakened, minor infections can become more serious and can lead to gangrene. A weak immune system can be caused by: